Photomasks including shadowing elements therein and related methods and systems

ABSTRACT

A photomask for patterning an integrated circuit device using a patterning radiation may include a transparent substrate, a pattern of radiation blocking regions, an array of radiation blocking regions, and an array of shadowing elements. The transparent substrate may have first and second opposing surfaces, and the pattern of radiation blocking regions may be on at least one of the first and/or second surfaces of the transparent substrate. Moreover, the pattern of radiation blocking regions may define a pattern to be transferred to the integrated circuit substrate. The array of shadowing elements may be provided within the transparent substrate between the first and second opposing surfaces wherein a shadowing element of the array has a light transmittance characteristic different than that of an adjacent portion of the transparent substrate. Moreover, a transmittance of the patterning radiation through a portion of the transparent substrate including the array of shadowing elements may be greater than approximately 20%. Related methods and systems are also discussed.

RELATED APPLICATIONS

[0001] The present application claims the benefit of priority as acontinuation-in-part from U.S. application Ser. No. 10/623,616 filedJul. 22, 2003, which claims the benefit of priority from KoreanApplication No. 2002-61046 filed Oct. 7, 2002. The present applicationalso claims the benefit of priority from Korean Application No.P2003-0084715 filed Nov. 26, 2003. The disclosures of all of the abovereferenced U.S. and Korean applications are hereby incorporated hereinin their entirety by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to the field of integrated circuitsand more particularly to photomasks used to pattern integrated circuitdevices and related methods and systems.

BACKGROUND

[0003] Photomasks are used in the patterning of integrated circuitdevices, and a conventional photomask may include microscopic images ona transparent substrate. As shown in FIG. 9, a photomask 901 may includea transparent substrate 903 (such as a glass and/or quartz substrate)with a microscopic image provided in a patterned layer 905 (such as apatterned layer of chrome) on a surface of the transparent substrate903. The microscopic image may be transferred from the photomask to aphotosensitive layer (such as photoresist) on a integrated circuit waferusing photolithographic techniques wherein patterning radiation (such aslight) is transmitted through the photomask onto the photosensitivelayer. Accordingly, portions of the photosensitive layer correspondingto openings in the patterned layer of chrome 905 are selectively exposedto the patterning radiation, while portions of the photosensitive layercorresponding to chrome portions of the patterned layer are masked fromthe patterning radiation. After exposure to the patterning radiationthrough the photomask, the photosensitive layer can be developed to formthe desired pattern in the photosensitive layer. The photosensitivelayer having the desired pattern can then be used as an etching mask fora layer of the integrated circuit device.

[0004] A critical dimension of an integrated circuit pattern may bedefined as a width of a line or space that has been identified as beingcritical to the device being fabricated. Portions of the pattern on thetransparent substrate may include a same critical dimension acrossdifferent portions of the photomask, and the critical dimension isideally reproduced uniformly in the photosensitive layer acrossdifferent portions of the integrated circuit device. A uniformity of acritical dimension formed at different portions of an integrated circuitdevice, formed at different integrated circuit devices on a samesemiconductor wafer, and formed on different semiconductor wafers mayvary, however, even when using a same photomask.

[0005] According to current photolithographic technologies, a photomaskmay include a pattern for a layer of a single integrated circuit deviceor a small number of adjacent integrated circuit devices, but not forall integrated circuit devices on a wafer. Accordingly, the photomaskmay need to be “scanned” or “stepped” to separately expose differentparts of a same photosensitive layer on a same wafer. For a photomaskincluding a pattern for a layer of a single integrated circuit device,the photomask may need to be sequentially aligned to each integratedcircuit device on the wafer and a separate dose of patterning radiationmay need to be provided for each integrated circuit device.

[0006] Non-uniformity of a critical dimension across a semiconductorwafer and/or from wafer to wafer using a same mask may be a result, forexample, of variations in coating the photosensitive layer, variationsin exposing the photosensitive layer to the patterning radiation,variations in developing the photosensitive layer after exposure,variations in baking the photosensitive layer, and/or variations inetching a layer on the wafer using the patterned photosensitive layer asa mask. Non-uniformities of a critical dimension across a sameintegrated circuit device may be a result, for example, of differencesin intensities of patterning radiation reaching the photosensitive layeron the integrated circuit device.

[0007] Even if critical dimensions of the patterned layer of thephotomask are provided without error, characteristics of the exposureapparatus and/or of the photomask may introduce non-uniformities incritical dimensions formed on a photosensitive layer. For example, acritical dimension of a pattern formed in a photosensitive layer at acenter of an integrated circuit device may generally be larger than acritical dimension of a pattern formed in the same photosensitive layerat an edge of the same integrated circuit device. This effect may be dueto diffraction of the patterning radiation passing through the patternedlayer of the photomask.

[0008] As shown in FIG. 10, patterning radiation 1001 may be provided toa backside of the transparent substrate 1005 opposite the patternedlayer 1007. Moreover, the patterning radiation 1001 may be provided witha relatively uniform distribution of illumination intensity asillustrated by solid line 1021. The patterning radiation may alsopropagate through the transparent substrate 1005 with a relativelyuniform distribution of illumination intensity as illustrated by solidline 1023. A uniformity of illumination intensity passing throughopenings in the patterned layer 1007, however, may vary across thesubstrate as illustrated by the dotted line 1025. The uniformity ofillumination intensity passing through the openings in the patternedlayer 1007 may vary, for example, because diffraction of light passingthrough openings in the patterned layer 1007 may be stronger at thecenter of the photomask 1003 than at edges of the photomask 1003. Aresulting distribution of critical dimensions across a device beingpatterned is illustrated by the line 1027.

SUMMARY

[0009] According to embodiments of the present invention, a photomaskmay be provided for patterning an integrated circuit device using apatterning radiation. For example, the photomask may include atransparent substrate, a pattern of radiation blocking regions, and anarray of shadowing elements. The transparent substrate may have firstand second opposing surfaces, and the pattern of radiation blockingregions may be provided on at least one of the first and/or secondsurfaces of the transparent substrate. In addition, the pattern ofradiation blocking regions may define a pattern to be transferred to theintegrated circuit substrate. The array of shadowing elements may beprovided within the transparent substrate between the first and secondopposing surfaces wherein shadowing elements of the array have a lighttransmittance characteristic different than that of an adjacent portionof the transparent substrate. Moreover, a transmittance of thepatterning radiation through a portion of the transparent substrateincluding the array of shadowing elements may be greater thanapproximately 20%.

[0010] A shadowing element of the array may have an index of refractionthat is different than that of an adjacent portion of the transparentsubstrate, and an average of center-to-center spacings of the shadowingelements within the array may be at least approximately 6 μm. Moreparticularly, an average of center-to-center spacing of the shadowingelements within the array may be at least approximately 8 μm. Thetransmittance of the patterning radiation through portions of thetransparent substrate including the array of shadowing elements may begreater than approximately 70%.

[0011] The photomask may also include a second array of shadowingelements within the transparent substrate between the first and secondopposing surfaces, and shadowing elements of the second array may have alight transmittance characteristic different than that of an adjacentportion of the transparent substrate. A transmittance of the patterningradiation through a portion of the transparent substrate including thesecond array of shadowing elements may be greater than approximately20%, and the transmittance of the patterning radiation through theportion of the transparent substrate including the second array may bedifferent than the transmittance of the patterning radiation though theportion of the transparent substrate including the first array.

[0012] In addition, the first array of shadowing elements may beconfigured to provide a first illumination condition for a first portionof the integrated circuit substrate, and the second array of shadowingelements may be configured to provide a second illumination conditionfor a second portion of the integrated circuit substrate wherein thefirst and second illumination conditions are different. The firstillumination condition may be one of annular illumination, dipoleillumination, or quadrapole illumination, and the second illuminationcondition may be another of annular illumination, dipole illumination,or quadrapole illumination. An average of center-to-center spacings ofthe shadowing elements within the first array may be different than anaverage of center-to-center spacings of the shadowing elements withinthe second array. Moreover, the transmittance of the patterningradiation through portions of the transparent substrate including thefirst and second arrays of shadowing elements may be greater thanapproximately 70%.

[0013] The array of shadowing elements may be configured to provide aholographic pattern used to generate a hologram on the integratedcircuit device, or the array of shadowing elements may be configured asa fresnel lens. In addition, the pattern of radiation blocking regionsmay be a pattern of a metal such as chrome. A diameter of a shadowingelement in the array may be in the range of approximately 0.1 μm to 4μm, and more particularly, in the range of approximately 0.3 μm to 1 μm.

[0014] According to additional embodiments of the present invention, amethod may be provided for forming a photomask for patterning anintegrated circuit device using a patterning radiation. For example, themethod may include providing a transparent substrate, forming a patternof radiation blocking regions, and forming an array of shadowingelements. The transparent substrate may have first and second opposingsurfaces, and the pattern of radiation blocking regions may be formed onat least one of the first and/or second surfaces of the transparentsubstrate. Moreover, the pattern of radiation blocking regions maydefine a pattern to be transferred to the integrated circuit device. Thearray of shadowing elements may be formed within the transparentsubstrate between the first and second opposing surfaces whereinshadowing elements of the array have a light transmittancecharacteristic different than that of an adjacent portion of thetransparent substrate. In addition, a transmittance of the patterningradiation through a portion of the transparent substrate including thearray of shadowing elements may be greater than approximately 20%.

[0015] The method may also include providing a pellicle on thetransparent substrate, and the array of shadowing elements may be formedwith the pellicle on the substrate. Forming the array of shadowingelements may include providing laser radiation to portions of thetransparent substrate for a shadowing element of the array. Moreparticularly, a burst of laser radiation having a duration on the orderof approximately 10⁻¹⁵ seconds may be provided for each of the shadowingelements of the array, and each burst of laser radiation may be on theorder of approximately 10⁶ to 10⁷ W/cm². In addition, providing laserradiation to portions of the transparent substrate for each shadowingelement of the array may generate a micro-explosion within thetransparent substrate for each shadowing element of the array.

[0016] A shadowing element of the array may have an index of refractionthat is different than that of an adjacent portion of the transparentsubstrate. An average of center-to-center spacings of the shadowingelements within the array may be at least approximately 6 μm, and moreparticularly, at least approximately 8 μm, and the transmittance of thepatterning radiation through portions of the transparent substrateincluding the array of shadowing elements may be greater thanapproximately 70%.

[0017] According to still additional embodiments of the presentinvention, a method of patterning an integrated circuit device mayinclude providing an integrated circuit substrate having aphotosensitive layer thereon, and projecting patterning radiationthrough a photomask to the photosensitive layer on the integratedcircuit substrate. More particularly, the photomask may include atransparent substrate, a pattern of radiation blocking regions, and anarray of shadowing elements. The transparent substrate may have firstand second opposing surfaces, and the pattern of radiation blockingregions may be on at least one of the first and/or second surfaces ofthe transparent substrate. More particularly, the pattern of radiationblocking regions may define a pattern to be transferred to theintegrated circuit device. The array of shadowing elements may beprovided within the transparent substrate between the first and secondopposing surfaces wherein a shadowing element of the array has a lighttransmittance characteristic different than that of an adjacent portionof the transparent substrate. In addition, a transmittance of thepatterning radiation through a portion of the transparent substrateincluding the array of shadowing elements may be greater thanapproximately 20%.

[0018] According to yet additional embodiments of the present invention,a system for patterning an integrated circuit device using patterningradiation may include a chuck, a photomask, and a radiation source. Thechuck may be configured to receive an integrated circuit substratehaving a photosensitive layer thereon, and the photomask may include atransparent substrate having first and second opposing surfaces, apattern of radiation blocking regions, and an array of shadowingelements. The pattern of radiation blocking regions may be provided onat least one of the first and/or second surfaces of the transparentsubstrate, and the pattern of radiation blocking regions may define apattern to be transferred to the integrated circuit substrate. The arrayof shadowing elements may be provided within the transparent substratebetween the first and second opposing surfaces wherein a shadowingelement of the array has a light transmittance characteristic differentthan that of an adjacent portion of the transparent substrate. Inaddition, a transmittance of the patterning radiation through a portionof the transparent substrate including the array of shadowing elementsmay be greater than approximately 20%. The system may also include aradiation source configured to project radiation through the photomaskto the photoresist layer on the integrated circuit substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a cross-sectional view of a photomask according toembodiments of the present invention.

[0020]FIG. 2 is a cross-sectional view illustrating variations inillumination intensities using photomasks according to embodiments ofthe present invention.

[0021]FIG. 3 is a cross-sectional view of another photomask according toembodiments of the present invention.

[0022]FIG. 4 is a plan view of a portion of a photomask includingdifferent regions according to embodiments of the present invention.

[0023]FIG. 5 is a block diagram illustrating systems and methods forforming arrays of shadowing elements according to embodiments of thepresent invention.

[0024]FIGS. 6a-d are photographs illustrating arrays of shadowingelements according to embodiments of the present invention.

[0025]FIG. 7 is a graph illustrating transmittances of different arraysof shadowing elements according to embodiments of the present invention.

[0026]FIG. 8 is a block diagram illustrating patterning systems andmethods according to embodiments of the present invention.

[0027]FIG. 9 is a cross-sectional view of a conventional photomask.

[0028]FIG. 10 is a cross-sectional view of a conventional photomask andrelative attenuations of patterning radiation passing therethrough.

DETAILED DESCRIPTION

[0029] The present invention will now be described more fully withreference to the accompanying drawings, in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as being limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the concept of the invention to those skilled in the art. In thedrawings, the size and the thickness of layers and regions areexaggerated for clarity. It will also be understood that when a layer isreferred to as being on another layer or substrate, it can be directlyon the other layer or substrate, or intervening layers may also bepresent. It will also be understood that when a layer or element isreferred to as being connected to or coupled to another layer orelement, it can be directly connected to or coupled to the other layeror element, or intervening layers or elements may also be present.

[0030] A photomask 111 for patterning an integrated circuit substrateaccording to embodiments of the present invention is illustrated in thecross-sectional view of FIG. 1. The photomask 111 may include atransparent substrate 101 (such as a glass or quartz substrate), anarray(s) of shadowing elements 105 within a volume of the transparentsubstrate 101 between first and second surfaces of the transparentsubstrate, and a pattern of radiation blocking (or opaque) regions 103on at least one of the first or second surfaces of the transparentsubstrate 101. The pattern of radiation blocking regions 103 may definea pattern to be transferred to the integrated circuit substrate, andeach shadowing element 105 within the array(s) may have a lighttransmittance characteristic different than that of an adjacent portionof the transparent substrate.

[0031] More particularly, a shadowing element 105 may have an index ofrefraction that is different than that of an adjacent portion of thetransparent substrate 101. In addition, a transmittance of thepatterning radiation through portions of the transparent substrateincluding the array(s) of shadowing elements 105 is at leastapproximately 50%. Also, the pattern of radiation blocking regions 103may be a patterned layer of a metal such as chrome, and a diameter of ashadowing element in the array(s) may be in the range of approximately0.1 μm to 4 μm, and more particularly, in the range of approximately 0.3μm to 1 μm.

[0032] The array(s) of shadowing elements 105 may be two-dimensional asshown in FIG. 1 such that the shadowing elements are in approximately asame plane in the photomask. More particularly, the shadowing elementsmay be arranged in arrays of rows and columns of shadowing elements withcenter-to-center spacings of shadowing elements of different arraysdiffering to provide different transmittance characteristics atdifferent portions of the photomask. For example, center-to-centerspacings of a first array 105 a of shadowing elements at a centralportion of the photomask may be less than center-to-center spacings ofsecond and third arrays 105 b and 105 c of shadowing elements at edgeportions of the photomask. Accordingly, a transmittance of patterningradiation through the first array 105 a at the center of the photomaskcan be less than a transmittance of patterning radiation through thesecond and third arrays 105 b and 105 c of shadowing elements at edgeportions of the photomask.

[0033] By providing different transmittances at different portions ofthe mask, a uniformity of patterning radiation intensity transmittedthrough the photomask 101 may be improved, and a uniformity of criticaldimensions patterned on an integrated circuit device can be improved. Asdiscussed above, diffraction generated by the radiation blocking pattern103 may affect an attenuation of patterning radiation passingtherethrough differently in different portions of the photomask. Forexample, diffraction generated by the radiation blocking pattern 103 maycause a greater attenuation of patterning radiation at edges of thephotomask than at the center of the photomask. The array(s) 105 ofshadowing elements may compensate for this non-uniformity of attenuationby providing a greater attenuation through the array 105 a at the centerof the photomask and by providing less attenuation through the arrays105 b-c at edges of the photomask. According to particular embodiments,a transmittance through the array(s) 105 of shadowing elements may bevaried within the range of approximately 98% to 100% to improve auniformity of patterning radiation provided at an integrated circuitdevice being patterned (with 100% being the transmittance of patterningradiation through a portion of the transparent substrate withoutshadowing elements).

[0034] As shown in FIG. 2, a source of patterning radiation may providepatterning radiation 201 of approximately uniform intensity across anentirety of the photomask 101. The line 207 is provided to show that anillumination intensity distribution for the patterning radiation 201entering the transparent substrate 101 is approximately uniform acrossthe entirety of the photomask. As discussed above, the array(s) 105 ofshadowing elements may be arranged so that a density of the shadowingelements is greater in a central portion of the substrate and so that adensity of the shadowing elements decreases as a distance from thecenter of the substrate increases. Accordingly, a transmittance throughthe array(s) 105 may be greatest near the edges of the substrate, andthe transmittance through the array(s) 105 may be the least near thecenter of the substrate.

[0035] The solid line 203 illustrates a relative attenuation oftransmittance of patterning radiation through different portions of thearray(s) 105 of shadowing elements. As discussed above, diffraction ofthe patterning radiation passing through the radiation blocking pattern103 may result in a greater attenuation of patterning radiation at edgesof the photomask 111 as illustrated by the dotted line 205. Accordingly,effects of varying transmittance through different portions of thearray(s) 105 of shadowing elements and effects of diffraction throughthe radiation blocking pattern 103 may be offset so that anapproximately uniform intensity of patterning radiation is transmittedthrough the substrate 101 and the radiation blocking pattern 103 asillustrated by the solid line 211. Moreover, the line 209 illustratesthat critical dimensions (CDs) across an integrated circuit device beingpatterned can be made approximately uniform using an array(s) ofshadowing elements according to embodiments of the present invention.

[0036] Moreover, factors other than diffraction through the radiationblocking pattern may affect the uniformity of critical dimensions on anintegrated circuit device being patterned. As shown in FIG. 3, thecritical dimensions CD1, CD2, and CD3 of a pattern of photosensitivelayer 301 (such as photoresist) may vary from relatively small (CD1) onone side of an integrated circuit device 303 being patterned torelatively large (CD3) on the other side of the integrated circuitdevice being patterned when using the photomask 311 without shadowingelements. The solid lines of the patterned photosensitive layer 301illustrate dimensions of the pattern when formed using the photomask 311prior to forming shadowing elements therein.

[0037] With knowledge of the CD non-uniformities resulting when thephotomask is used without shadowing elements, a design for shadowingelements can be determined to improve the CD uniformity. The photomask311 includes a transparent substrate 315 and a radiation blockingpattern 317 (such as a chrome pattern) on the transparent substrate 315.As shown, the radiation blocking pattern 317 defines the pattern to betransferred to the photosensitive layer 301 on the integrated circuitdevice 303. After CD non-uniformities have been determined and a designfor shadowing elements has been determined, arrays of shadowing elements319 a and 319 b can be formed in the transparent substrate 315 betweenfirst and second surfaces thereof. The shadowing elements can be formed,for example, using a femto second laser as discussed in greater detailbelow. Spacings, sizings, and/or placements of the shadowing elements,for example, may be determined empirically using trial and error and/orusing simulation.

[0038] As shown in FIG. 3, the region of the transparent substrate 315without any shadowing elements may provide a relatively hightransmittance of patterning radiation therethrough, and the region ofthe transparent substrate 315 including the array 319 b of shadowingelements may provide a relatively low transmittance of patterningradiation therethrough. The region of the transparent substrate 315including the array 319 a of shadowing elements may provide a mediumtransmittance of patterning radiation therethrough less than therelatively high transmittance through the region without shadowingelements and greater than the relatively low transmittance through theregion including the array 319 b of shadowing elements. As discussedabove, differences in transmittance in absolute terms may be relativelysmall with all regions of the substrate providing a transmittance ofgreater that 97% for the patterning radiation 321. By adding the arraysof shadowing elements, the uniformity of critical dimensions in thephotosensitive layer 301 being patterned can be improved as shown by thedashed lines.

[0039] The transmittance through the arrays of shadowing elements can bevaried, as discussed above, by providing differences in spacings of theshadowing elements in the different arrays. As shown in FIG. 3, forexample, spacings in the array 319 a may be greater than in the array319 b. The transmittance can also be varied by providing shadowingelements of a first size in one array and by providing shadowingelements of a second size in a second array. The shadowing elements ofarray 319 a, for example, may be larger than shadowing elements of array319 b. The transmittance can also be varied by providing differentnumbers of layers of shadowing elements in different arrays. The array319 a, for example, may include a single layer of shadowing elementswhile the array 319 b may include multiple layers of shadowing elements.According to embodiments of the present invention, differences inspacings of shadowing elements, differences in sizes of shadowingelements, differences in layers of shadowing elements, and/ordifferences in other characteristics of arrays of shadowing elements maybe used individually or in combination to improve photomask performance.

[0040] Referring again to FIG. 1, an average of center-to-centerspacings of shadowing elements within the array(s) 105 may be at leastapproximately 6 μm, and more particularly, an average ofcenter-to-center spacing of shadowing elements may be at leastapproximately 8 μm. A transmittance of the patterning radiation throughportions of the transparent substrate including the array(s) ofshadowing elements may thus be greater than approximately 70%, andaccording to particular embodiments, greater than 97%. As discussedabove, a transmittance through portions of the transparent substrateincluding the array(s) of shadowing elements may be varied betweenapproximately 98% and 100% (with 100% being the transmittance ofpatterning radiation through a portion of the transparent substratewithout shadowing elements).

[0041] The photomask of FIG. 1 may thus include a first array 105 a ofshadowing elements between first and second surfaces of the transparentsubstrate 101 at a central portion thereof, and a second array 105 b ofshadowing elements between first and second surfaces of the transparentsubstrate 101 at an edge portion thereof. Moreover, transmittances ofthe patterning radiation through the portions of the transparentsubstrate including the first and second arrays of shadowing elementsmay be greater than approximately 50%. The transmittance of thepatterning radiation through the portion of the transparent substrateincluding the second array, however, may be different than thetransmittance of the patterning radiation though the portion of thetransparent substrate including the first array. As discussed above,transmittance through portions of the substrate including the secondarray 105 b may be greater than transmittance through portions of thesubstrate including the first array 105a, for example, to compensate fordifferences in illumination intensities due to diffraction caused by theradiation blocking pattern 103. More particularly, transmittancesthrough the different arrays of shadowing elements may vary between 98%and 100% (with 100% being the transmittance of patterning radiationthrough portions of the substrate without shadowing elements). Forexamples, different transmittances may be provided by providingdifferent average center-to-center spacings of shadowing elements withindifferent arrays.

[0042] In addition or in an alternative, different arrays may be used toprovide different illumination conditions for different regions of anintegrated circuit device being patterned. When fabricating anintegrated circuit memory device (such as a dynamic random access memorydevice), different illumination conditions may be provided for memorycell array regions and for peripheral circuit regions. For example, afirst array 150 a of shadowing elements may be configured to provide adipole illumination condition for a memory cell array region of anintegrated circuit memory device, and a second array 150 b of shadowingelements may be configured to provide an annular illumination conditionfor a peripheral circuit region of the same integrated circuit memorydevice.

[0043] Conventionally, an illumination condition may be determined by anaperture through which the patterning radiation is transmitted beforereaching the photomask so that a same illumination condition is providedover the entirety of an integrated circuit device being patterned.According to embodiments of the present invention, different arrays ofshadowing elements in a photomask may be used to provide differentillumination conditions on different parts of an integrated circuitdevice during a same exposure step. An array of shadowing elements in atransparent substrate of a photomask may thus be configured to provide,for example, one of an annular illumination condition, a dipoleillumination condition, a quadrapole illumination condition, or acustomized illumination condition. Different arrays of shadowingelements in a photomask may thus be used to provide differentillumination conditions on different regions of an integrated circuitdevice being patterned. In an alternative, an array(s) of shadowingelements in a photomask may be used to provide a uniform illuminationcondition (such as an annular illumination condition, a dipoleillumination condition, a quadrapole illumination condition, or acustomized illumination condition) across an integrated circuit devicebeing patterned without requiring a particular aperture between a sourceof patterning radiation and the photomask.

[0044] An integrated circuit memory device, for example, may includerectangular memory cell array regions with peripheral circuit regionsseparating the memory cell array regions. Accordingly, as shown in FIG.4, a photomask 401 used to pattern such a device may include memory cellarray regions 403 a-d and peripheral circuit regions 405 separating thememory cell array regions. A radiation blocking pattern on a surface ofthe photomask may define the pattern to be transferred to aphotosensitive layer on the integrated circuit memory device, and anarray or arrays of shadowing elements between transparent surfaces mayprovide one or more illumination conditions for particular portions ofthe integrated circuit memory device being patterned. For example, firstarrays of shadowing elements in the memory cell array regions 403 a-d ofthe photomask 401 may provide a dipole illumination condition(s) formemory cell array regions of the integrated circuit memory device, andsecond arrays of shadowing elements in the peripheral circuit regions405 may provide an annular illumination condition(s) for peripheralcircuit regions of the integrated circuit memory device during a samemasking step.

[0045] In addition or in an alternative, one or more arrays of shadowingelements may be configured to provide a holographic pattern used togenerate a hologram on the integrated circuit device being patterned,and different holographic patterns may be provided by different arraysof shadowing elements in the same photomask. Similarly, one or morearrays of shadowing elements may be configured as a fresnel lens, anddifferent fresnel lenses may be provided by different arrays ofshadowing elements in the same photomask.

[0046] Shadowing elements may be formed in photomasks according toembodiments of the present invention using a system such as thatillustrated in FIG. 5. As discussed above with respect to FIGS. 1-3, aphotomask may include a radiation blocking pattern (such as a patternedlayer of chrome) on a transparent substrate wherein the radiationblocking pattern corresponds to a pattern to be transferred to aphotosensitive layer on an integrated circuit device. Moreover, thephotomask can be used to pattern a test photosensitive layer prior toforming shadowing elements to determine what, if any, critical dimensionnon-uniformities may need to be corrected.

[0047] A desired array(s) of shadowing elements can be determined forthe photomask based on the information obtained from the patterned testphotoresist layer. By forming shadowing elements after forming theradiation blocking pattern, the shadowing elements can be aligned to theradiation blocking pattern. In addition, a pellicle can be placed on thephotomask after forming the radiation blocking pattern but beforepatterning the test photosensitive layer and before forming shadowingelements. Accordingly, the radiation blocking pattern can be protectedfrom dust before and during formation of the shadowing elements.

[0048] Shadowing elements 511 can then be formed between surfaces of thetransparent substrate while maintaining the pellicle on the radiationblocking pattern of the photomask. While not shown in FIG. 5, theradiation blocking pattern and the pellicle may be on a surface of thetransparent substrate 501 opposite the surface through which the laserradiation is introduced. The laser radiation may be generated by a lasersource 503 (such as a femto second laser), and the laser radiation maybe expanded using one or more expanders 505. The beam steering device507 may direct the expanded laser radiation toward the transparentsubstrate 501, and the focusing device 509 may focus the laser radiationto a particular point where a shadowing element is to be formed.

[0049] The laser radiation can be directed to an X-Y coordinate (lateralposition) of a particular shadowing element on the transparent substrate501 using the beam steering device 507 and/or by physically moving thetransparent substrate in the X-Y directions (perpendicular relative tothe direction of the laser radiation). The laser radiation can bedirected to a Z coordinate (depth) of a particular shadowing element inthe transparent substrate 501 using a depth of focus provided by thefocusing device 509 and/or by physically moving the transparentsubstrate in the Z direction (parallel to the direction of the laserradiation).

[0050] Each shadowing element may be formed using a pulsed burst oflaser radiation directed to and focused on a predetermined locationwithin a volume of the transparent substrate 501 between first andsecond surfaces thereof. A pulsed burst of laser radiation used to forma shadowing element, for example, may have a duration on the order ofapproximately 10⁻¹⁵ second. The pulsed burst of laser radiation maygenerate a micro-explosion at the predetermined location within thetransparent substrate. Computerized control of shadowing elementplacement may be used to generate 2 and/or 3 dimensional array(s) ofshadowing elements within the volume of the transparent substrate 501between first and second surfaces of the transparent substrate.

[0051] When forming an individual shadowing element 511, the lasersource 503 may generate a pulse of laser radiation having a duration onthe order of 10⁻¹⁵ seconds, and the laser radiation may be expandedusing one or more expanders 505 and then focused using focusing device509. The steering device 507 may provide that the laser radiation isdirected to desired X-Y coordinates of the transparent substrate, andthe focusing device 509 may provide that the laser radiation is focusedat a desired depth (Z coordinate) within the transparent substrate.

[0052] More particularly, the focusing device 509 may focus the laserradiation so that on the order of approximately 10⁶ W/cm² to 10⁷ W/cm²is concentrated at the depth within the transparent substrate at whichthe shadowing element is to be formed. With this concentration ofenergy, avalanche photon adsorption and/or ionization may generate aplasma zone in the transparent substrate (without melting or evaporatingthe substrate). Localized heating and cooling may result in a shock wavethat generates a damaged zone having a morphologically differentstructure than that of surrounding portions of the transparent substrate501. The resulting damaged zone thus provides a shadowing element 511that may have a refractive index different than (either greater than orless than) that of surrounding portions of the transparent substrate501. Light scattering at shadowing elements 511 thus formed may be usedto change an imaging intensity of patterning radiation passingtherethrough.

[0053] An individual shadowing element formed as discussed above mayhave a diameter in the range of approximately 0.1 μm to 4.0 μm, and moreparticularly, in the range of approximately 0.3 μm to 1.0 μm. Sizes ofshadowing elements may be varied, for example, by varying an intensityof laser radiation, a duration of the laser radiation, size of the beam,and/or a number of laser radiation pulses used to form the shadowingelement. In addition or in an alternative, a size of a shadowing element511 may be increased by forming two or more overlapping shadowingelements.

[0054] Moreover, the steering device 507 and the focusing device 509 mayalign the shadowing elements within the volume of the transparentsubstrate 501 using a previously formed radiation blocking patternformed on the opposite side of the transparent substrate. In addition, apellicle may be maintained on the radiation blocking pattern whileforming the shadowing elements so that the radiation blocking pattern isshielded from dust. In an alternative, the shadowing elements may beformed before forming the radiation blocking pattern, and the radiationblocking pattern may be aligned relative to the shadowing elements. Inanother alternative, both the radiation blocking pattern and theshadowing elements may be aligned relative to some other indicatorformed independently of either the radiation blocking pattern or theshadowing elements.

[0055] Arrays of shadowing elements formed as discussed above areillustrated in FIGS. 6a-d. In FIG. 6a, the shadowing elements arearranged in an array of rows and columns with an average ofcenter-to-center spacings of approximately 4.0 μm. In FIG. 6b, theshadowing elements are arranged in an array of rows and columns with anaverage of center-to-center spacings of approximately 6.0 μm. In FIG.6c, the shadowing elements are arranged in an array of rows and columnswith an average of center-to-center spacings of approximately 8.0 μm. InFIG. 6d, the shadowing elements are arranged in an array of rows andcolumns with an average of center-to-center spacings of approximately10.0 μm.

[0056] The graph of FIG. 7 illustrates measured transmittances ofradiation (of 248 nm wavelength) through substrates including arrays ofshadowing elements as illustrated in FIGS. 6a-d. More particularly,three sample transparent substrates were generated with each sampletransparent substrate including four arrays of shadowing elements withaverage center-to-center spacings of 4.0 μm, 6.0 μm, 8.0 μm, and 10.0μm. As shown, arrays of shadowing elements with average center-to-centerspacings of approximately 4.0 μm may provide a transmittance in therange of approximately 20% to 40%. Arrays of shadowing elements withaverage center-to-center spacings of approximately 6.0 μm may provide atransmittance in the range of approximately 50% to 60%. Arrays ofshadowing elements with average center-to-center spacings ofapproximately 8.0 μm may provide a transmittance in the range ofapproximately 70% to 80%. Arrays of shadowing elements with averagecenter-to-center spacings of approximately 10.0 μm may provide atransmittance in the range of approximately 85% to 90%. The reference of100% transmittance is measured with respect to a portion of thesubstrate free of shadowing elements. Moreover, a reduction intransmittance of approximately 2% may be sufficient to improve criticaldimension (CD) tolerances.

[0057] As discussed above, a depth of the shadowing elements in thetransparent substrate of a photomask may be determined by a position ofthe transparent substrate relative to the focusing device and by a focalpoint of the laser radiation from the focusing device. Moreover, theshadowing region of an integrated circuit device (being patterned) thatis affected by a shadowing element (or array of shadowing elements) maybe dependent on a distance of the shadowing element (or array ofshadowing elements) from the surface of the transparent substrate havingthe radiation blocking pattern thereon. By providing the shadowingelements within the transparent substrate close to the surface havingthe radiation blocking pattern thereon, a resulting shadowing region onthe integrated circuit device being patterned can be reduced. Control ofcritical dimensions (CD) can thus be provided with a resolution of lessthan approximately 1.26 mm. Stated in other words, shadowing elementsaccording to embodiments of the present invention may provide improvedresolution because the shadowing elements and the radiation blockinglayer can be separated by less than a full thickness of the transparentsubstrate of the photomask. Accordingly, control of CD uniformity can beimproved. Different arrays of shadowing elements may thus be used toprovide different CD controls and/or different illumination conditionson closely spaced regions of an integrated circuit device (such as cellarray and peripheral circuit regions).

[0058] Photo masks according to embodiments of the present invention maythus be used to pattern photosensitive layers as shown, for example, inFIG. 8. A source 801 may generate patterning radiation 803 a, such asradiation having a wavelength of approximately 248 nm. The patterningradiation 803 a is directed through a photomask 805 having shadowingelements 805 a within a volume of a transparent substrate 805 b thereof.A radiation blocking pattern 805 c (such as a chrome pattern) defines apattern that is transferred to a photosensitive layer 807 a on anintegrated circuit substrate 807 b using modified patterning radiation803 b. Moreover, the integrated circuit substrate 807 b may bemaintained in a desired orientation relative to the source 801 and thephotomask 805 c using chuck 809.

[0059] More particularly, the patterning radiation 803 a from the source801 is modified by passing through the photomask 805 (including theshadowing elements 805 a and the radiation blocking pattern 805 c) toprovide the modified patterning radiation 803 b. For example, theradiation blocking pattern 805 c may define a pattern to be transferredto the photosensitive layer, and the shadowing elements 805 a may beprovided in arrays configured to compensate for effects caused bydiffraction through the radiation blocking pattern 805 c. In addition orin the alternative, the shadowing elements 805 a may be configured toprovide one or more illumination conditions (such as a dipoleillumination condition, a quadrapole illumination condition, an annularillumination condition, and/or a customized illumination condition), toprovide a holographic pattern on the photosensitive layer 807 a, and/orto provide a fresnel lens, and/or to provide different illuminationintensities. The photomask 805 may be formed as discussed above withrespect to FIGS. 5-7 to provide one or more functionalities discussedabove with respect to FIGS. 1-4.

[0060] While this invention has been particularly shown and describedwith reference to embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims.

That which is claimed is:
 1. A photomask for patterning an integratedcircuit device using a patterning radiation, the photomask comprising: atransparent substrate having first and second opposing surfaces; apattern of radiation blocking regions on at least one of the firstand/or second surfaces of the transparent substrate, the pattern ofradiation blocking regions defining a pattern to be transferred to theintegrated circuit substrate; and an array of shadowing elements withinthe transparent substrate between the first and second opposing surfaceswherein a shadowing element of the array has a light transmittancecharacteristic different than that of an adjacent portion of thetransparent substrate and wherein a transmittance of the patterningradiation through a portion of the transparent substrate including thearray of shadowing elements is greater than approximately 20%.
 2. Aphotomask according to claim 1 wherein a shadowing element of the arrayhas an index of refraction that is different than that of an adjacentportion of the transparent substrate.
 3. A photomask according to claim1 wherein an average of center-to-center spacings of the shadowingelements within the array is at least approximately 6 μm.
 4. A photomaskaccording to claim 3 wherein an average of center-to-center spacing ofthe shadowing elements within the array is at least approximately 8 μm.5. A photomask according to claim 1 wherein the transmittance of thepatterning radiation through portions of the transparent substrateincluding the array of shadowing elements is greater than approximately70%.
 6. A photomask according to claim 1 further comprising: a secondarray of shadowing elements within the transparent substrate between thefirst and second opposing surfaces wherein a shadowing element of thesecond array has a light transmittance characteristic different thanthat of an adjacent portion of the transparent substrate, wherein atransmittance of the patterning radiation through a portion of thetransparent substrate including the second array of shadowing elementsis greater than approximately 20%, and wherein the transmittance of thepatterning radiation through the portion of the transparent substrateincluding the second array is different than the transmittance of thepatterning radiation though the portion of the transparent substrateincluding the first array.
 7. A photomask according to claim 6 whereinthe first array of shadowing elements is configured to provide a firstillumination condition for a first portion of the integrated circuitsubstrate and wherein the second array of shadowing elements isconfigured to provide a second illumination condition for a secondportion of the integrated circuit substrate wherein the first and secondillumination conditions are different.
 8. A photomask according to claim7 wherein the first illumination condition comprises one of annularillumination, dipole illumination, or quadrapole illumination, andwherein the second illumination condition comprises another of annularillumination, dipole illumination, or quadrapole illumination.
 9. Aphotomask according to claim 6 wherein an average of center-to-centerspacings of the shadowing elements within the first array is differentthan an average of center-to-center spacings of the shadowing elementswithin the second array.
 10. A photomask according to claim 9 whereinthe transmittance of the patterning radiation through portions of thetransparent substrate including the first and second arrays of shadowingelements is greater than approximately 70%.
 11. A photomask according toclaim 1 wherein the array of shadowing elements is configured to providea holographic pattern used to generate a hologram on the integratedcircuit device.
 12. A photomask according to claim 1 wherein the arrayof shadowing elements is configured as a fresnel lens.
 13. A photomaskaccording to claim 1 wherein the pattern of radiation blocking regionscomprises a pattern of a metal.
 14. A photomask according to claim 13wherein the metal comprises chrome.
 15. A photomask according to claim 1wherein a diameter of a shadowing element in the array is in the rangeof approximately 0.1 μm to 4 μm.
 16. A photomask according to claim 15wherein a diameter of a shadowing element in the array is in the rangeof approximately 0.3 μm to 1 μm.
 17. A method of forming a photomask forpatterning an integrated circuit device using a patterning radiation,the method comprising; providing a transparent substrate having firstand second opposing surfaces; forming a pattern of radiation blockingregions on at least one of the first and/or second surfaces of thetransparent substrate, the pattern of radiation blocking regionsdefining a pattern to be transferred to the integrated circuit device;and forming an array of shadowing elements within the transparentsubstrate between the first and second opposing surfaces wherein ashadowing element of the array has a light transmittance characteristicdifferent than that of an adjacent portion of the transparent substrateand wherein a transmittance of the patterning radiation through aportion of the transparent substrate including the array of shadowingelements is greater than approximately 20%.
 18. A method according toclaim 17 further comprising: providing a pellicle on the transparentsubstrate prior to forming the array of shadowing elements wherein thearray of shadowing elements is formed while maintaining the pellicle onthe substrate.
 19. A method according to claim 17 wherein forming thearray of shadowing elements comprises providing laser radiation toportions of the transparent substrate for a shadowing element of thearray.
 20. A method according to claim 19 wherein forming the array ofshadowing elements comprises providing a burst of laser radiation havinga duration on the order of approximately 10⁻¹⁵ seconds for each of theshadowing elements of the array.
 21. A method according to claim 19wherein forming the array of shadowing elements comprises providing aburst of laser radiation on the order of approximately 10⁶ to 10⁷ W/cm².22. A method according to claim 19 wherein providing laser radiation toportions of the transparent substrate for a shadowing element of thearray generates a micro-explosion within the transparent substrate forthe shadowing element of the array.
 23. A method according to claim 17wherein a shadowing element of the array has an index of refraction thatis different than that of an adjacent portion of the transparentsubstrate.
 24. A method according to claim 17 wherein an average ofcenter-to-center spacings of the shadowing elements within the array isat least approximately 6 μm.
 25. A method according to claim 24 whereinan average of center-to-center spacing of the shadowing elements withinthe array is at least approximately 8 μm.
 26. A method according toclaim 17 wherein the transmittance of the patterning radiation throughportions of the transparent substrate including the array of shadowingelements is greater than approximately 70%.
 27. A method according toclaim 17 further comprising: forming a second array of shadowingelements within the transparent substrate between the first and secondopposing surfaces wherein a shadowing element of the second array has alight transmittance characteristic different than that of an adjacentportion of the transparent substrate, wherein a transmittance of thepatterning radiation through a portion of the transparent substrateincluding the second array of shadowing elements is greater thanapproximately 20%, and wherein the transmittance of the patterningradiation through the portion of the transparent substrate including thesecond array is different than the transmittance of the patterningradiation though the portion of the transparent substrate including thefirst array.
 28. A method according to claim 27 wherein the first arrayof shadowing elements is configured to provide a first illuminationcondition for a first portion of the integrated circuit substrate andwherein the second array of shadowing elements is configured to providea second illumination condition for a second portion of the integratedcircuit substrate wherein the first and second illumination conditionsare different.
 29. A method according to claim 28 wherein the firstillumination condition comprises one of annular illumination, dipoleillumination, or quadrapole illumination, and wherein the second type ofillumination comprises another of annular illumination, dipoleillumination, or quadrapole illumination.
 30. A method according toclaim 27 wherein an average of center-to-center spacings of theshadowing elements within the first array is different than an averageof center-to-center spacings of the shadowing elements within the secondarray.
 31. A method according to claim 30 wherein the transmittance ofthe patterning radiation through portions of the transparent substrateincluding the first and second arrays of shadowing elements is greaterthan approximately 70%.
 32. A method according to claim 17 wherein thearray of shadowing elements is configured to provide a holographicpattern used to generate a hologram on the integrated circuit device.33. A method according to claim 17 wherein the array of shadowingelements is configured as a fresnel lens.
 34. A method according toclaim 17 wherein the pattern of radiation blocking regions comprises apattern of a metal.
 35. A method according to claim 34 wherein the metalcomprises chrome.
 36. A method according to claim 17 wherein a diameterof a shadowing element in the array is in the range of approximately 0.1μm to 4 μm.
 37. A method according to claim 36 wherein a diameter of ashadowing element in the array is in the range of approximately 0.3 μmto 4 μm.
 38. A method according to claim 17 wherein forming an array ofshadowing elements is performed prior to forming a pattern of radiationblocking regions.
 39. A method of patterning an integrated circuitdevice, the method comprising: providing an integrated circuit substratehaving a photosensitive layer thereon; projecting patterning radiationthrough a photomask to the photosensitive layer on the integratedcircuit substrate, the photomask including, a transparent substratehaving first and second opposing surfaces, a pattern of radiationblocking regions on at least one of the first and/or second surfaces ofthe transparent substrate, the pattern of radiation blocking regionsdefining a pattern to be transferred to the integrated circuit device;and an array of shadowing elements within the transparent substratebetween the first and second opposing surfaces wherein a shadowingelement of the array has a light transmittance characteristic differentthan that of an adjacent portion of the transparent substrate andwherein a transmittance of the patterning radiation through a portion ofthe transparent substrate including the array of shadowing elements isgreater than approximately 20%.
 40. A method according to claim 39wherein a shadowing element of the array has an index of refraction thatis different than that of an adjacent portion of the transparentsubstrate.
 41. A method according to claim 39 wherein an average ofcenter-to-center spacings of the shadowing elements within the array isat least approximately 6 μm.
 42. A method according to claim 41 whereinan average of center-to-center spacing of the shadowing elements withinthe array is at least approximately 8 μm.
 43. A method according toclaim 39 wherein the transmittance of the patterning radiation throughportions of the transparent substrate including the array of shadowingelements is greater than approximately 70%.
 44. A method according toclaim 39 wherein the photomask further includes: a second array ofshadowing elements within the transparent substrate between the firstand second opposing surfaces wherein a shadowing element of the secondarray has a light transmittance characteristic different than that of anadjacent portion of the transparent substrate, wherein a transmittanceof the patterning radiation through a portion of the transparentsubstrate including the second array of shadowing elements is greaterthan approximately 20%, and wherein the transmittance of the patterningradiation through the portion of the transparent substrate including thesecond array is different than the transmittance of the patterningradiation though the portion of the transparent substrate including thefirst array.
 45. A method according to claim 44 wherein the first arrayof shadowing elements is configured to provide a first illuminationcondition for a first portion of the integrated circuit substrate andwherein the second array of shadowing elements is configured to providea second illumination condition for a second portion of the integratedcircuit substrate wherein the first and second illumination conditionsare different.
 46. A method according to claim 45 wherein the firstillumination condition comprises one of annular illumination, dipoleillumination, or quadrapole illumination, and wherein the secondillumination condition comprises another of annular illumination, dipoleillumination, or quadrapole illumination.
 47. A method according toclaim 44 wherein an average of center-to-center spacings of theshadowing elements within the first array is different than an averageof center-to-center spacings of the shadowing elements within the secondarray.
 48. A method according to claim 47 wherein the transmittance ofthe patterning radiation through portions of the transparent substrateincluding the first and second arrays of shadowing elements is greaterthan approximately 70%.
 49. A method according to claim 39 wherein thearray of shadowing elements is configured to provide a holographicpattern used to generate a hologram on the integrated circuit device.50. A method according to claim 39 wherein the array of shadowingelements is configured as a fresnel lens.
 51. A method according toclaim 39 wherein the pattern of radiation blocking regions comprises apattern of a metal.
 52. A method according to claim 51 wherein the metalcomprises chrome.
 53. A method according to claim 39 wherein a diameterof a shadowing element in the array is in the range of approximately 0.1μm to 4 μm.
 54. A method according to claim 53 wherein a diameter of ashadowing element in the array is in the range of approximately 0.3 μmto 1 μm.
 55. A system for patterning an integrated circuit device usingpatterning radiation, the system comprising: a chuck configured toreceive an integrated circuit substrate having a photosensitive layerthereon; a photomask including a transparent substrate having first andsecond opposing surfaces, a pattern of radiation blocking regions on atleast one of the first and/or second surfaces of the transparentsubstrate the pattern of radiation blocking regions defining a patternto be transferred to the integrated circuit substrate, and an array ofshadowing elements within the transparent substrate between the firstand second opposing surfaces wherein a shadowing element of the arrayhas a light transmittance characteristic different than that of anadjacent portion of the transparent substrate and wherein atransmittance of the patterning radiation through a portion of thetransparent substrate including the array of shadowing elements isgreater than approximately 20%; and a radiation source configured toproject radiation through the photomask to the photoresist layer on theintegrated circuit substrate.
 56. A system according to claim 55 whereina shadowing element of the array has an index of refraction that isdifferent than that of an adjacent portion of the transparent substrate.57. A system according to claim 55 wherein an average ofcenter-to-center spacings of the shadowing elements within the array isat least approximately 6 μm.
 58. A system according to claim 57 whereinan average of center-to-center spacing of the shadowing elements withinthe array is at least approximately 8 μm.
 59. A system according toclaim 55 wherein the transmittance of the patterning radiation throughportions of the transparent substrate including the array of shadowingelements is greater than approximately 70%.
 60. A system according toclaim 55 further comprising: a second array of shadowing elements withinthe transparent substrate between the first and second opposing surfaceswherein a shadowing element of the second array has a lighttransmittance characteristic different than that of an adjacent portionof the transparent substrate, wherein a transmittance of the patterningradiation through a portion of the transparent substrate including thesecond array of shadowing elements is greater than approximately 20%,and wherein the transmittance of the patterning radiation through theportion of the transparent substrate including the second array isdifferent than the transmittance of the patterning radiation though theportion of the transparent substrate including the first array.
 61. Asystem according to claim 60 wherein the first array of shadowingelements is configured to provide a first illumination condition for afirst portion of the integrated circuit substrate and wherein the secondarray of shadowing elements is configured to provide a secondillumination condition for a second portion of the integrated circuitsubstrate wherein the first and second illumination conditions aredifferent.
 62. A system according to claim 61 wherein the firstillumination condition comprises one of annular illumination, dipoleillumination, or quadrapole illumination, and wherein the secondillumination condition comprises another of annular illumination, dipoleillumination, or quadrapole illumination.
 63. A system according toclaim 60 wherein an average of center-to-center spacings of theshadowing elements within the first array is different than an averageof center-to-center spacings of the shadowing elements within the secondarray.
 64. A system according to claim 63 wherein the transmittance ofthe patterning radiation through portions of the transparent substrateincluding the first and second arrays of shadowing elements is greaterthan approximately 70%.
 65. A system according to claim 55 wherein thearray of shadowing elements is configured to provide a holographicpattern used to generate a hologram on the integrated circuit device.66. A system according to claim 55 wherein the array of shadowingelements is configured as a fresnel lens.
 67. A system according toclaim 55 wherein the pattern of radiation blocking regions comprises apattern of a metal.
 68. A system according to claim 67 wherein the metalcomprises chrome.
 69. A system according to claim 55 wherein a diameterof a shadowing element in the array is in the range of approximately 0.1μm to 4 μm.
 70. A system according to claim 69 wherein a diameter of ashadowing element in the array is in the range of approximately 0.3 μmto 1 μm.